Removable flotation means and water drive assembly for snowmobiles

ABSTRACT

A conversion kit including a pontoon assembly, steering rudder and propeller with interconnected drive shaft and power transmission is utilized to adapt a snowmobile for use as a water vehicle by being removably mounted thereon. Turning linkage attached to the rudder is connected to the ski spindle steering mechanism of the snowmobile for operation thereby. The transmission of the propeller drive assembly includes a power input shaft sized to be rotatably supported transversely of the snowmobile frame in the bearings where the front drive axle for the snowmobile track is normally mounted, the power input shaft being driven by the same sprocket and chain arrangement from the snowmobile engine ordinarily employed to drive the front drive axle.

[ 1 Mar.7,1972

United States Patent Lanning et al.

[54] REMOVABLE FLOTATION MEANS AND 3,521,595 7/1970 WATER DlRI'V EASSEMBLY FOR SNOWMOBILES [72] Inventors: Charles T. Lanning, 7305Clinton Ave.,

Primary ExaminerAndrew H. Farrell Attorney-Williamson, Palmatier & Bains7] ABSTRACT A conversion kit including a pontoon assembly, steeringrudder and propeller with interconnected drive shaft and Richfield,Minn. 55423; James T. Cook, 5 North Broadway, Watertown, S. Dak. 57201[22] Filed: Oct. 31, 1969 [21] Appl. No.: 873,778

[52] US. ...ll5/l,ll5/0.5

[Sl] Int. Cl. ....B60f3/00 [58] Field ofSearch..................ll5/l,O.5A

axle for the snowmobile track is normally mounted, the power input shaftbeing driven by the same sprocket and chain ar- Relerences Citedrangement from the snowmobile engine ordinarily employed to drive thefront drive axle.

UN lTED STATES PATENTS 2,325,532 7/1943 Miller l5/0.5 A 6 Claims, 7Drawing Figures PATENTED AR 7 I972 SHEET 1 [1F 3 INVENTORS Gamma 7.mums;

JAMES Z' C'OOK PATENTEDMAR- 71972 3.646.904

SHEET 3 [IF 3 INVENTORS aYA L J'Z'LAJl/WJAIGI JAMES 7. 000K REMOVABLEFLOTATION MEANS AND WATER DRIVE ASSEMBLY FOR SNOWMOBILES BRIEF SUMMARYOF THE INVENTION There is wide spread and increasing use in the northernsections of the United States and in Canada of snowmobiles asrecreational, camping and hunting vehicles. The snowmobile is arelatively expensive piece of recreational equipment having only alimited time span of usage during the winter months when snow and frozenlakes and rivers afford an opportunity for their proper and normal useby means of the engine driven tracks and skiis on which the snowmobilesare supported. The primary purpose of this invention is to provide aconversion kit which may be quickly and easily removably assembled to asnowmobile to permit the snowmobile to be used as a water vehicle in thesummer time, and thus to make the snowmobile a multiseasonalrecreational vehicle.

This basic objective is realized by utilizing a conversion kit comprisedof flotation means, preferably in the form of a preassembled pontoonstructure, a steering rudder with attached turning linkage, and apropeller drive assembly including a power transmission, all of whichcomponents are constructed to permit their removable mounting on asnowmobile with a minimum of time and effort. In the preferredembodiment of my invention, this is accomplished by a pontoon assemblycomprised of a pair of elongated pontoons which are constructed andarranged to extend along opposite sides of a snowmobile to provideflotation support means therefor and which serve as mounting means forthe steering rudder and turning linkage attached thereto.

A particularly advantageous feature of my invention resides in theutilization of cables as the linkage means for turning the rudder, apair of cables being attached to the rudder and extending lengthwisealong the opposed pontoons of the flotation assembly around pulleyssecured to the pontoons, each of the turning cables having a couplingdevice at the forward end thereof constructed and located for detachableconnection to the pair of turning spindles at the forward end of thesnowmobile to which skiis are normally attached. By virtue of thisarrangement, the steering mechanism of the snowmobile normally utilizedfor turning the skiis at the forward end of the snowmobile isconveniently employed for turning the rudder when using the snowmobilein water.

As a further beneficial feature of the snowmobile conversion kit of thisinvention, the propeller drive assembly is rendered easily mountable onthe snowmobile for power drive by the snowmobile engine by means of apower input shaft to the transmission of the propeller drive assembly ofsuch a length and diameter as to be interchangeable with the front driveaxle for the snowmobile tracks. ln converting a snowmobile for water useby means of my conversion kit, the front drive axle, tracks, skiis andbogie wheel units for supporting the track are removed. The aforesaidpower input shaft of the propeller drive transmission is then mountedtransversely of the snowmobile frame within the bearings normallyutilized to rotatably support the front drive axle, one end of the powerinput shaft being connected to the engine-driven sprocket nor mallyutilized to drive the front drive axle for the snowmobile track.

The snowmobile conversion kit of this invention is further uniquelydistinguished by vertically adjustable mounting means for the steeringrudder and propeller and its drive shaft supporting these componentsfrom the snowmobile body in such a way that they may be adjustedupwardly or downwardly to provide proper operation in water and to avoidinterference with a trailer on which the converted snowmobile may betransported.

These and other objects and advantages of our invention will becomereadily apparent as the following description is read in conjunctionwith the accompanying drawings wherein like reference numerals have beenused to designate like elements throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exploded, perspectiveview showing the manner inwhich the pontoon assembly and steeringportion of the conversion kit of this invention is mounted on asnowmobile;

FIG. 2 is a side, elevation view, partially in section, showing thevarious components of our conversion kit mounted on a snowmobile toadapt it for water operation;

FIG. 3 is a bottom plan view of the rear end of the converted snowmobileof FIG. 2;

FIG. 4 is a rear, elevation view of the converted snowmobile of FIG. 2;

FIG. 5 is a horizontal section view of the gear assembly fortransmitting power to the propeller drive shaft portion of theconversion kit;

FIG. 6 is a vertical section view taken along lines 6-6 of FIG. 3 andshowing the lift mechanism for the propeller drive shaft; and

FIG. 7 is a side elevation view, partially broken away, showing amodified version of a snowmobile conversion apparatus wherein thepropeller drive assembly is located directly under the front drive axleposition of the snowmobile.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,I have shown in FIG. 1 the flotation assembly generally designated byreference numeral 1, and including in combination therewith steeringrudder 2 and the rudder turning linkage of the conversion kit of thisinvention. The flotation assembly 1 and steering rudder 2 have beenconstructed and arranged for removable mounting on a snowmobile ofconventional design designated by reference numeral 3 and shown inexploded perspective relation to flotation assembly 1 to indicate theorientation of the flotation assembly with respect to the snowmobilewhen assembled thereto. Snowmobile 3 is of standard, and knownconstruction including a body frame 4 with side boards 5 thereon whichserve as rests for the operators and passenger's feet. Hood 6 enclosesan engine (not shown) which drives a front axle by means of an ordinarychain and sprocket arrangement, the front drive axle being utilized toimpart rotary movement to endless tracks supported on sprockets andbogie wheels on both sides of the snowmobile body at the rear endthereof. The tracks on which the snowmobile is ordinarily supported anddriven, as well as the sprockets and bogie wheels therefor have beenremoved, along with the pair of skiis normally utilized to support thefront end of the snowmobile on snow and ice, in order to ready thesnowmobile for the mounting of the wateroperation conversion kitthereon. The manner of assembling the skiis, drive tracks, tracksprockets and bogie wheels to the snowmobile is well known in the art,and since these components form no part of this invention they have notbeen shown. The skiis are ordinarily connected to steering spindles 7and 8 at the front end of the snowmobile, these spindles being rotatableby means of a conventional steering linkage connected to handle bar 10through steering column 12. A front bumper bar 14 extends around enginehood 6, and back rest frame 16 for seat 18 is strengthened, reinforcedand protected by rear, frame bars 20 and 22, more fully describedhereinafter with respect to FIGS. 2, 3 and 4.

Flotation assembly 1 preferably takes the form of a pair of elongatedpontoons 24 and 25 secured together by front and rear cross braces 26and 27 prior to the installation thereof on snowmobile 3. Extendinglengthwise along pontoons 24 and 25 are right angle flange strips 28 and29 which are affixed to pontoons 24 and 25 at their lower ends as bywelding in the case of metal pontoons, or by fasteners if the pontoonsare made of plastic or fiberglass. Horizontally extending bracket plates30 and 31 secured to the front and rear ends of flange strips 28 and 29are welded or otherwise affixed to the wall surfaces of pontoons 24 and25 and assist in holding flange strips 28 and 29 thereto as well asproviding a support base for the outer ends of cross braces 26 and 27.Clamps 33 and 34 are utilized to hold the ends of cross braces 26 and 27in secure engagement with horizontal flange portions 28a and 29a offlange strips 28 and 29. Depending downwardly and inwardly from flangestrips 28 and 29 and affixed to horizontal flange portions 28a and 29athereof by fasteners 36 and 37 are splash skirts 38 and 39. Horizontallyextending flanges 38a and 39a at the lower end of splash skirts 38 and39 are adapted to rest upon and be secured to side boards of thesnowmobile when the flotation assembly 1 is affixed thereto. The purposeof splash plates 38 and 39 is to keep water from splashing up on sideboards 5 where the driver and passengers will be resting their feet. Thedisposition of splash skirts 38 and 39 with respect to side boards 5 ofthe snowmobile is shown most clearly in FIGS. 3 and 4.

Rudder 2 is positioned at the rear or stern end of pontoon assembly 1and includes an upright rudder shaft 40 having steering rudder 2 securedto the bottom end thereof. Rudder shaft 40 is rotatably contained withinsleeve 42 which is rigidly secured to cross brace 27 of the pontoonassembly by means of a U-bolt 44 embracing sleeve 42 and attached tobracket plate 46 which is welded or otherwise firmly affixed to crossbrace 27. U-bolt 44 and its complementary bracket plate 46 appear morefully in FIG. 4. Rudder shaft 40 is vertically adjustable within sleeve42 for reasons hereinafter explained, as well as being rotatable thereinabout a vertical axis defined by the longitudinal axis of sleeve 42.Cotter pin 48 serves to hold rudder shaft 40 within sleeve 42 whenrudder 2 is in its lowered position of use as shown in FIG. 1. Turningmovement for rudder 2 is provided by means of a linkage arrangementwhich preferably takes the fonn of a pair of turning cables 50 and 51directed around pulleys 52 and 53 located at the front and rear ends ofpontoons 24 and 25. As may be noted with reference to FIGS. 2, 3 and 4,pulleys 52 and 53 are attached to flange strips 28 and 29 by means ofmounting links 54 and 55. Continuing to refer to FIGS. 1 through 4, weutilize coil spring connectors 56 and 57 to connect cables 50 and 51 atone end thereof to turning arm 58 on rudder shaft 40. Coil springs 56and 57 serve to return rudder 2 to a straight center position and holdit there after it has been rotated one direction or the other during asteering maneuver by cables 50 or 51. From their point of attachment torudder shaft 40, cables 50 and 51 extend forwardly around pulleys 52 and53 to coupling means in the form of eye" bolts 60 and 61 at the forwardends thereof. Eye bolts 60 and 61 are constructed and arranged forattachment to ski mounting and turning spindles 7 and 8 at the forwardend of snowmobile 3. Spindles 7 and 8 include as integral portionsthereof sleeve connectors 62 and 63 within which the shanks of eye bolts60 and 61 are received and secured by nuts 64 in the manner indicated inphantom lines on the snowmobile in FIG. 1. The skiis which support thefront end of the snowmobile during winter operation have bifurcatedcoupling portions on the upright coupling spindles thereof which areremovably secured to sleeve connectors 62 and 63 by fasteners extendingtherethrough.

The removable attachment of pontoon assembly 1 to snowmobile 3 isaccomplished by means of U-bolts 66 on cross brace 27 and by clamps 68affixed to horizontal flange portions 28a and 29a of flange mountingstrips 28 and 29. Before mounting the pontoon and rudder assembly onsnowmobile 3, the front end skiis, drive tracks, and front and rearaxles, drive sprockets and supporting bogie wheels for the tracks arefirst removed so that the snowmobile will be in the condition shown inFIG. 1 for attachment of the water-operation conversion kit thereto. Thesnowmobile body rests on pontoon assembly I with pontoons 24 and 25extending longitudinally along the opposite sides of the snowmobile sideframes 4 in the arrangement shown in FIGS. 3 and 4. Pontoon assembly 1is secured to the snowmobile by hooking clamps 68 over the top ofrearwardly extending portions 14a of front bumper bar 14 as is indicatedin FIGS. I and 2, and by utilizing U-bolts 66 to attach cross brace 27of the pontoon assembly to transversely extending rear frame bar 22 ofthe snowmobile in the arrangement shown in FIGS. 2, 3 and 4. Cross brace27 rests on top of frame bar 22 and U-bolts 66 are fastened tocomplementary clamping plates 67 which are of C-shape to fit around thetop of cross brace 27. Support is further provided for the front end ofsnowmobile 3 by the abutting engagement of rearwardly extending portions14a of bumper bar 14 along the top of flange portions 28a and 29a offlange strips 28 and 29. On certain types of snowmobiles, it will bepossible to so locate front cross brace 26 of the pontoon assembly as tobe able to clamp it to the front end of bumper bar 14 of the snowmobileas a further means of insuring that the pontoon assembly will besecurely held in place on the snowmobile body and frame. With pontoonassembly 1 in place on the snowmobile as shown in FIGS. 2, 3 and 4,lower flange portions 38a and 39a of splash plates 38 and 39 will beresting on top of side boards 5 and are secured thereto by means offasteners 70 shown in FIG. 4. Eye bolts 60 and 61 at the forward end ofturning cables 50 and 51 are inserted within sleeves 62 and 63 onturning spindles 7 and 8 and removably held in place therein by means ofretention nuts 64. By inserting eye bolts 60 and 61 in place withinsleeves 62 and 63 with the eye portion thereof disposed inwardly andcables 50 and 51 extending forwardly therefrom around pulleys 52 and 53at the forward end of pontoons 24 and 25, adequate turning leverage isobtained to impart sufficient movement to cables 50 and 51 that rudder 2will respond to steering movement of handle bar 10. The turning radiusof the snowmobile in water, and the responsiveness of rudder 2 toturning movements of steering handle 10 can further be adjusted byloosening retention nuts 64 and shifting eye bolts 60 and 61 lengthwisewithin sleeves 62 and 63 of steering spindles 7 and 8 to obtain more orless turning leverage.

It is to he noted that pontoons 24 and 25 are provided with laterallyprojecting flanges 72 and 73 on both sides thereof, these flangesextending along the entire length of the pontoons and functioning assupplementary flotation devices to prevent pontoons 24 and 25 fromsinking too deep into the water under the weight of snowmobile 3 and thepassengers riding therein.

In addition to being supported on cross brace 27 of the pontoon assemblyby U-bolt 44, the rudder assembly is further secured by utilizing asecond U-bolt 74 and complementary bracket plate 76 to hold the upperend of rudder sleeve 42 to upper frame bar 20a of rear frame bar 20. InFIGS. 2 and 4, rudder shaft 40 is shown in the lower position of use inwhich it is set when the snowmobile has been converted into awatercraft. With rudder shaft 40 in its lowermost position, rudder 2will be under the surface of the water to provide proper steering actionfor the snowmobile. For those occasions when it is desired to transportthe snowmobile on a trailer with the watercraft conversion kit mountedthereon, rudder shaft 40 is raised within sleeve 42 in order to elevaterudder 2 to a position wherein it will not interfere with the trailer.This is accomplished by removing cotter pin 48 from rudder shaft 40,sliding shaft 40 upwardly within sleeve 42 and then inserting cotter pin48 through a second aperture (not shown) in shaft 40 to hold it in itselevated position.

In order to provide motive power for the converted snowmobile when it isused as a water craft, the conversion kit further includes a propeller78 and its associated drive as sembly which will now be described withreference to FIGS. 2, 3 and 4. In the embodiment of our invention shownin these figures, propeller 78 is mounted on the end of an elongateddrive or power output shaft 80 which is contained within an elongatedhousing 82 secured at its inner end to a transmission case 84. As isshown in FIG. 5, transmission case 84 houses a drive gear secured to theinner end of propeller drive shaft 80. Power is transmitted from inputshaft 88 to output or propeller drive shaft 80 by the driving engagementof bevel pinion or gear 86 with driven gear 90. As a particularlyadvantageous feature of our power drive unit, input shaft 88 is of sucha length and diameter as to be supportable transversely between sideframe members 4 of snowmobile 3 within bearings 92 and 93 within whichthe front drive axle for the snowmobile tracks is normally rotatablysupported. This drive axle has been removed, along with the tracks andtheir drive sprockets and supporting bogie wheels in order to place thesnowmobile in condition to receive the water conversion kit. Bearings 92and 93 are secured to side frame members 4 by means of brackets 94.Shaft 88 is held in place by means of a lock collar and set screw 95, 96on bearing 92, the releasing of lock collar 95 by loosening set screw 96permitting the front drive axle to be shifted laterally within bearings92 and 93 and removed from the bearings prior to the mounting of powerinput shaft 88 therein. As may be noted with respect to FIGS. 2 and 3,power input shaft 88 utilized to transmit power to propeller 78 isattached at one end thereof to drive sprocket 98 which is driven bychain 100 which extends around a complementary sprocket coupled to thecrank shaft of the snowmobile engine. The sprocket and chain drivearrangement 98, 100 is normally utilized to supply rotary power to thefront drive axle ordinarily supported between bearings 92 and 93 fordriving the track sprockets. Thus, there is no need to modify the powerdrive arrangement of the snowmobile other than to remove the front driveaxle and to mount power input shaft 88 of the propeller drive unit inits place between bearings 92 and 93.

For the purpose of insuring that propeller 78 has a proper head of waterin which to operate so that it will be able to propel the snowmobileadequately in water, a cavitation plate 102 is supported over propeller78 in the manner shown in FIGS. 2, 3 and 6. Horizontally extendingcavitation plate 102 is so located in overlying relation to propeller 78that it will normally be disposed a short distance of at least one inchbelow the surface of the water to assist in insuring a liquid head freeof bubbles within which propeller 78 can operate. Cavitation plate 102thus functions in the same, well-known manner as do similar cavitationplates or devices normally employed in combination with boat and shippropellers. Cavitation plate 102 is secured at its inner end to driveshaft housing 82, as by welding, and is supported therefrom by aT-shaped bracket 104 welded to the top of drive shaft housing 82 and tothe underside of plate 102.

Since the portion of the propeller drive unit including elongated,rearwardly and downwardly extending drive shaft 80, drive shaft housing82 and propeller 78 would normally interfere with a trailer on which thesnowmobile in the form of a watercraft might be transported, provisionhas also been made for raising and lowering the drive shaft assembly topermit trailering and beaching of the snowmobile as well as itsoperation in shallow water. To this end, a lifting mechanism isconnected to the lower end of drive shaft housing 82 by attachment tocavitation plate 102. As appears most clearly in FIGS. 2, 3 and 6, thelifting mechanism is comprised of interconnected linkage arms 106 and108, lower linkage arms 108 being connected to cavitation plate 102 bymeans of connecting rod 110 extending transversely through upright,apertured ears 112 which are welded or otherwise secured to the top ofcavitation plate 102. Upper linkage arms 106 are secured to rotary shaft114 of the lift mechanism for rotation therewith by means of C-clamps116 to which they are threadedly attached. Shaft 114, along with thelinkage mechanism including arms 106 and 108 forms a part of theconversion kit, shaft 114 being rotatably supported between side framemembers 4 of the snowmobile within bearings 118 provided for thatpurpose. Holes must be drilled in side frame members 4 to permit themounting of bearings 118 and shaft 114 transversely therebetween. Liftmechanism operating level 120 is connected to one end of rotary shaft114, lever 120 being movable forwardly and rearwardly to impart rotarymovement to shaft 114. A ratchet mechanism comprised of a notchedretention member 122 and pivotal release arm 124 is utilized to holdlever 120 in the various positions to which it might be moved. Theratchet mechanism appears most clearly in FIG. 1. The lower end ofrelease arm 124 may be engaged and disengaged from any one of thenotches within retention plate 122 by applying pressure to hand gripportion 125 thereof and pivoting arm 124 about pivotal connection 126with operating lever 120. In order to lower the entire propeller anddrive assembly, operating lever 120 is moved to the rearward positionshown in solid lines in FIG. 2 wherein linkage arms 106 and 108 willdepend downwardly as shown. The depth at which propeller 78 will besubmerged, and thus the operating and drive characteristics of thepropeller can be adjusted by setting operating lever 120 in'various onesof the notches of ratchet plate 122. In order to raise propeller 78 anddrive shaft housing 82 upwardly for beaching the snowmobile water craft,driving it in shallow water or placing it on a trailer, operating lever120 is moved forwardly to thereby rotate shaft 114 in a counterclockwisedirection as viewed in FIG. 2. This will cause linkage arm 106 to pivotrearwardly and upwardly with the result that the lower end of propellerdrive shaft 82 and propeller 78 will be raised up within the tunnel orrecess space defined between snowmobile side frames 4. It will of coursebe appreciated that as the rear end of propeller drive shaft housing 82is raised or lowered by the lift mechanism it will pivot freely at itsinner end about the horizontal axis defined by power input shaft 88, byvirtue of the rotation of shaft 88 within bearings 92 and 93.

We contemplate that the installation of our conversion kit on asnowmobile could further be simplified by rotatably supporting shaft 114of the lift mechanism between bearing brackets provided on the rear endof pontoon assembly 1. Such bearing brackets for shaft 114 could bemounted, for example, on cross brace 27. This modification wouldeliminate the necessity for mounting shaft 114 between side frames 4 ofthe snowmobile during the conversion operation.

In FIG, 7, we have shown a modified version of the propeller drive unitfor our conversion kit, In this arrangement, power input SHAFT 88 andtransmission gears 86 and are utilized in the same manner as explainedabove to transmit power by means of a chain and sprocket drivearrangement from the snowmobile engine to the drive shaft for thepropeller 78a. In this case, however, a standard lower power unit of anoutboard motor generally designated by reference numeral 128 isconnected directly to the underside of transmission case 84 with drivengear 90 being oriented substantially horizontally on a verticallydepending drive shaft (not shown) extending downwardly directly underpower input shaft 88 within the housing of power unit 128. The powerunit includes an integral cavitation plate 102a disposed under the waterlevel directly above propeller 78a. Power unit 128 may likewise bepivoted upwardly within the space defined between snowmobile side frames4 by means of operating lever and a modified linkage mechanism securedrotary shaft 114. Linkage arm 106a is directly connected to shaft 114for rotation therewith, and is pivotally attached at its lower end to anelongated linkage arm I30 connected to the housing of power unit 128.The forward movement of operating lever 120 will serve to rotate primarylinkage arm 106a rearwardly to pull elongated linkage arm 130 rearwardlyand upwardly with the result that the power unit will pivot upwardlyabout the horizontal axis of power input shaft 88 to raise propeller 78and the lower end of power unit 128 for beaching or trailering the watercraft-snowmobile.

What we claim is:

1. In combination with a snowmobile, flotation, steering and drive meansto permit said snowmobile to operate as a water vehicle comprising:

a pontoon assembly having a pair of elongated pontoons extending alongeach side of the body of said snowmobile and removably secured thereto;

a steering rudder detachably connected to said snowmobile and havinglinkage means connected thereto for providing turning movement thereofabout a vertical axis, said linkage means extending forwardly from saidrudder and being connected to the ski spindle turning mechanism of saidsnowmobile for operation thereby;

a power output shaft drivingly connected to a propeller supported belowsaid snowmobile for imparting movement to said snowmobile in water, saidpower output shaft being connected by power transmission means to apower input shaft rotatably supported between the side frames of saidsnowmobile in bearings within which the front drive shaft of saidsnowmobile is normally supported, said power input shaft being connectedat one end thereof to the engine driven sprocket normally utilized fordriving said front drive shaft of said snowmobile. 2. A snowmobilemodified for water operation as defined in claim 1 wherein:

said rudder includes an upright shaft vertically slidable and adjustableto different elevations within a mounting sleeve secured to saidsnowmobile. 3. A snowmobile modified for water operation as defined inclaim 1 wherein:

said power output shaft is contained within an elongated housing securedat its inner end to a transmission case containing said powertransmission means and rotatable about the horizontal axis defined bysaid power input shaft, said elongated housing having a linkagemechanism connected thereto by means of which it may be lowered orraised into the space defined between said side frame of said snowmobileby pivotal movement about said horizontal axis. 4. A snowmobile modifiedfor water operation as defined in claim 1 wherein:

said power output shaft extends longitudinally rearwardly from saidpower input shaft within an elongated housing; and further including agenerally horizontally extending cavitation plate secured to saidelongated housing in overlying relation to said propeller. 5. Asnowmobile modified for water operation as defined in claim 4 wherein:

said elongated housing is pivotally supported at the inner end thereoffor pivotal movement about the horizontal axis defined by said rotatablysupported power input shaft; and

further including a lift mechanism having linkage means connected tosaid cavitation plate by means of which said power output shaft,elongated housing and propeller may be lowered and raised by pivotalmovement about said horizontal axis.

6. A conversion kit for adapting a snowmobile for use as a water vehiclecomprising:

flotation means removably attachable to a snowmobile;

a steering rudder at the rear end ofsaid flotation means;

linkage means connected to said rudder for providing turning movementthereof about a vertical axis, said linkage means extending forwardlyfrom said rudder and including coupling means at the forward end thereofparticularly constructed and located for detachable connection to theski spindle turning mechanism of said snowmobile; and

power transmission means including a power input shaft adapted to beconnected at one end thereof to the engine drive mechanism to which thefront drive shaft of said snowmobile is normally connected, said powerinput shaft being of such a length and diameter as to be rotatablysupportable transversely between the side frames of said snowmobilewithin the bearings normally provided in said side frames for rotatablysupporting the front drive shaft of said snowmobile, and said powertransmission means further including a power output shaft driven by saidpower input shaft through gear means and drivingly connected to apropeller for imparting movement to said snowmobile in water.

1. In combination with a snowmobile, flotation, steering and drive meansto permit said snowmobile to operate as a water vehicle comprising: apontoon assembly having a pair of elongated pontoons extending alongeach side of the body of said snowmobile and removably secured thereto;a steering rudder detachably connected to said snowmobile and havinglinkage means connected thereto for providing turning movement thereofabout a vertical axis, said linkage means extending forwardly from saidrudder and being connected to the ski spindle turning mechanism of saidsnowmobile for operation thereby; a power output shaft drivinglyconnected to a propeller supported below said snowmobile for impartingmovement to said snowmobile in water, said power output shaft beingconnected by power transmission means to a power input shaft rotatablysupported between the side frames of said snowmobile in bearings withinwhich the front drive shaft of said snowmobile is normally supported,said power input shaft being connected at one end thereof to the enginedriven sprocket normally utilized for driving said front drive shaft ofsaid snowmobile.
 2. A snowmobile modified for water operation as definedin claim 1 wherein: said rudder includes an upright shaft verticallyslidable and adjustable to different elevations within a mounting sleevesecured to said snowmobile.
 3. A snowmobile modified for water operationas defined in claim 1 wherein: said power output shaft is containedwithin an elongated housing secured at its inner end to a transmissioncase containing said power transmission means and rotatable about thehorizontal axis defined by said power input shaft, said elongatedhousing having a linkage mechanism connected thereto by means of whichit may be lowered or raised into the space defined between said sideframe of said snowmobile by pivotal movement about said horizontal axis.4. A snowmobile modified for water operation as defined in claim 1wherein: said power output shaft extends longitudinally rearwardly fromsaid power input shaft within an elongated housing; and furtherincluding a generally horizontally extending cavitation plate secured tosaid elongated housing in overlying relation to said propeller.
 5. Asnowmobile modified for water operation as defined in claim 4 wherein:said elongated housing is pivotally supported at the inner end thereoffor pivotal movement about the horizontal axis defined by said rotatablysupported power input shaft; and further including a lift mechanismhaving linkage means connected to said cavitation plate by means ofwhich said power output shaft, elongated housing and propeller may belowered and raised by pivotal movement about said horizontal axis.
 6. Aconversion kit for adapting a snowmobile for use as a water vehiclecomprising: flotation means removably attachable to a snowmobile; asteering rudder at the rear end of said flotation means; linkage meansconnected to said rudder for providing turning movement thereof about avertical axis, said linkage means extending forwardly from said rudderand including coupling means at the forward end thereof particularlyconstructed and located for detachable connection to the ski spindleturning mechanism of said snowmobile; and power transmission meansincluding a power input shaft adapted to be connected at one end thereofto the engine drive mechanism to which the front drive shaft of saidsnowmobile is normally connected, said power input shaft being of such alength and diameter as to be rotatably supportable transversely betweenthe side frames of said snowmobile within the bearings normally providedin said side frames for rotatably supporting the front drive shaft ofsaid snowmobile, and said power transmission means further including apower output shaft driven by said power input shaft through gear meansand drivingly connected to a propeller for imparting movement to saidsnowmobile in water.